1. Field of the Invention
The present invention relates to a method of manufacturing a surface-emitting-type semiconductor laser device having a buried structure wherein a burying part is formed around a buried part comprising an active region.
2. Description of Related Art
Generally, in the manufacturing process of the surface-emitting-type GaAlAs/GaAs semiconductor laser device having a buried structure, an active layer, a cladding layer, a cap layer and the like are crystal-grown on the surface of a GaAs substrate respectively in a predetermined sequence, and thereafter a mask layer consisting of an oxide film made of silicon dioxide (SiO.sub.2) or silicon nitride (Si.sub.3 N.sub.4) is formed on the surface of the cap layer. Subsequently, a resist layer is formed on the surface of this mask layer, and patterning is applied to the mask layer, and thereafter etched part is formed by etching the circumference of the multilayer body with the resist layer acting as a mask. Subsequently, the resist layer is removed, and regrowth consisting of a plurality of blocking layers providing a current blocking function is formed around the etched part with the mask layer left intact. Thus, the etched part constitutes a buried part and the regrowth constitutes a burying part.
Then, in the conventional method as described above, an oxide film is used for the material of the mask layer, and therefore the active layer, the cladding layer, the cap layer and the like are formed continuously in a crystal growing apparatus. Thereafter, the substrate is taken outside from the crystal growing apparatus, and a separate vaporizing process for forming the mask layer is required to be provided. Also, in the etching process for forming the etched part to be buried by the regrowth, an etchant for GaAs and GaAlAs which are materials of the active layer, the cladding layer, the cap layer and the like which form the etched part hardly etches the oxide film such as silicon dioxide, and therefore the resist layer and the mask layer are left intact in the initially patterned state. Only the cladding layer, the active layer and the cap layer under the mask layer are etched. Then, when the etching has been completed, the portion under the mask layer is side-etched, and the portion under the mask layer is depressed inward with respect to the mask layer, that is, a so-called undercut is formed. As a result, there has been the problem that the mask layer might be peeled off at cleaning after the etching process, and the cladding layer, the active layer, the cap layer and the like lack uniformity, and a satisfactory reproductivity cannot be secured.